People now have until Tuesday to sign up for insurance via HealthCare.gov, the federal Centers for Medicare and Medicaid Services announced Monday. The previous deadline was Monday for those using the federal health insurance exchanges to secure coverage that will be in place on Jan.

This week’s deadline applies to people attempting to sign up for health insurance that will be in place on Jan. 1. The full enrollment period runs until March 31.

“The deadline for signing up for coverage to start Jan. 1 is today. We recognize that many have chosen to make their final decisions on today’s deadline and we are committed to making sure they can do so,” Julie Bataille, a spokeswoman for the Centers for Medicare and Medicaid Services, said in a written statement. “Anticipating high demand and the fact that consumers may be enrolling from multiple time zones, we have taken steps to make sure that those who select a plan through tomorrow will get coverage for Jan. 1.”

Traffic to HealthCare.gov exceeded 1 million visitors before 5:00 p.m. EST Monday, according to the Twitter account associated with the website. That nearly equaled the weekend total of 1.2 million and is more than five times the traffic last Monday, the Centers for Medicare and Medicaid Services reported.

That high demand was evident Monday morning, when HealthCare.gov, the portal to the health insurance exchanges in 36 states, began putting visitors into its queuing system because of high traffic. The Centers for Medicare and Medicaid Services said the 11th-hour change to the hard deadline for January enrollments was put into place because heavy use of the website or other technical problems could ensnare people. Health insurance companies were also consulted, the agency said.

“Health plans will continue to do everything they can to help consumers through the enrollment process and mitigate potential confusion or disruption caused by all of these last-minute changes to the rules and deadlines,” Robert Zirkelbach, a spokesman for the trade group America’s Health Insurance Plans, said in a written statement.

Enrollments made via the federal system by 11:59 p.m. EST Tuesday will qualify for January coverage, and these consumers have until Jan. 10 to pay their first premium. Individuals using the state-run exchanges in California, Colorado, Connecticut, Hawaii, Kentucky, Nevada, New York, Vermont and the District of Columbia must complete their enrollments Monday. Residents of Washington state who begin their enrollments Monday can complete them by Jan. 15 to secure coverage next month. Marylanders and Oregonians can enroll until Dec. 27, while Massachusetts residents, Minnesotans and Rhode Islanders have until Dec. 31.

In spite of the shift to Tuesday for enrollments via the federal system, the Obama administration urged consumers to act Monday. “Consumers should not wait until tomorrow. If you are aiming to get coverage Jan. 1, you should try to sign up today,” Bataille said in a separate written statement. Assistance will be provided to individuals who encounter problems with the system today, she said.

This story has been updated with information on HealthCare.gov web traffic for Monday and with Massachusetts’ new deadline, announced Monday. A statement from America’s Health Insurance Plans and a new statement from Julie Bataille were also added.